The invention relates to an adjustment mechanism for an automobile seat back.
In a known adjustment mechanism of the prior art as described in DE 30 13 304 C2, part of the wedge segments that form an eccentric cam and are tapered in opposite rotational directions are positioned on a bearing surface concentric to the axis of rotation. A pressure spring stretched between the broad frontal surfaces of the two wedge segments forces the wedge segments in opposing directions with the result that the eccentricity increases because of the spring""s effect.
A disadvantage to this known solution is that the length of the wedge segments, i.e., the angle formed by the effective supporting surfaces, is restricted. This restriction is essential to the system. Too great an effective length has the result that the front wedge segment in the direction of rotation does not adequately release the teeth as desired during actuation, but rather presses them together. In practice, the inner contact surface of both wedge segments is therefore relatively short. A relatively short contact surface leads to faster wear because the wedge segment may tip along its supporting surface.
Based on this state of the art, the present invention features an adjustment mechanism of the type known so that it is formed to be as resistant to wear as possible and to operate silently.
These goals are achieved by the present invention wherein the positioning of the wedge segments in a radial direction with one above the other and with opposite orientation allows the option of selecting an effective length of the wedge segments to be longer than that used in the state of the art, thus forming an articulated mechanism that is more resistant to wear. Because of the comparatively large potential wedge length, it is even possible not to use the entire wedge length, but rather only to provide supporting surfaces at the two ends, leaving the central area free. This promotes silence during operation and reduces manufacturing costs.